Method of synthesis for organic semiconducting polymers

ABSTRACT

A method of forming a polymer, the method comprising combining 4,7-bis(5-bromo-4-alkyl thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole, (3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane), and benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane), Pd2dba3 and P(o-tol)3 to form the polymer: 
     
       
         
         
             
             
         
       
     
     In this polymer, W is selected from the group consisting of: S, Se, O, and N-Q. Additionally, in this polymer Q is selected from the group consisting of: a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring. R 1 , R 2 , R 3 , R 4 , and R 5  are independently selected from the group consisting of: F, Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH 2 , —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO 3 X, —SO 2 X, —OH, —NO 2 , CF 3 , —SF 5 , a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring, and heteroaromatic rings. Additionally, in this polymer wherein the fused aromatic rings can be independently fused with groups consisting of: a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring; and the ratio of x is between 0.6 to 0.8 and y is between 0.2 and 0.4.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application orcontinuation-in-part application which claims the benefit of andpriority to U.S. Provisional Application Ser. No. 62/892,415 filed Aug.27, 2019, titled “Method of Synthesis for Organic SemiconductingPolymers,” which is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

This invention relates methods of synthesis of organic semiconductingpolymers.

BACKGROUND OF THE INVENTION

Solar energy using photovoltaics requires active semiconductingmaterials to convert light into electricity. Currently, solar cellsbased on silicon are the dominating technology due to their high powerconversion efficiency. Recently, solar cells based on organic materialsshowed interesting features, especially on the potential of low cost inmaterials and processing.

Organic photovoltaic cells have many potential advantages when comparedto traditional silicon-based devices. Organic photovoltaic cells arelight weight, economical in the materials used, and can be deposited onlow cost substrates, such as flexible plastic foils. However, organicphotovoltaic devices typically have relatively low power conversionefficiency (the ratio of incident photons to energy generated).

There exists a need for a polymer to create organic photovoltaic cellsthat has high power conversion efficiency while maintainingopen-circuitry voltage short-circuit current density, and fill factor.

BRIEF SUMMARY OF THE DISCLOSURE

A method of forming a polymer, the method comprising combining4,7-bis(5-bromo-4-alkylthiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane), andbenzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane), Pd2dba3and P(o-tol)3 to form the polymer:

In this polymer, W is selected from the group consisting of: S, Se, 0,and N-Q. Additionally, in this polymer Q is selected from the groupconsisting of: a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fusedsubstituted aromatic ring, and a fused unsubstituted aromatic ring. R₁,R₂, R₃, R₄, and R₅ are independently selected from the group consistingof: F, Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X,—C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH,—NO₂, CF₃, —SF₅, a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fusedsubstituted aromatic ring, and a fused unsubstituted aromatic ring, andheteroaromatic rings. Additionally, in this polymer wherein the fusedaromatic rings can be independently fused with groups consisting of: astraight-chain or branched carbyl, silyl, or hydrocarbyl, a branched orcyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, anda fused unsubstituted aromatic ring; and the ratio of x is between 0.6to 0.8 and y is between 0.2 and 0.4.

In another embodiment, a method of forming a polymer is taught where,the method comprises combining4,7-bis(5-bromo-4-alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane)Pd2dba3and P(o-tol)3 to form a mixture. The mixture is then degassed to form adegassed mixture. The degassed mixture is then heated to form a heatedmixture followed by cooling the heated mixture to form the polymer:

In this polymer the ratio of x is between 0.6 to 0.8 and y is between0.2 and 0.4.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts a conventional device architecture and an inverted devicearchitecture.

FIG. 2 depicts the creation of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 3 depicts the spectra of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 4 depicts the spectra of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 5 depicts the spectra of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 6a depicts the spectra of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 6b depicts the spectra of4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole.

FIG. 7 depicts the spectra of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole.

FIG. 8 depicts the spectra of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole.

FIG. 9a depicts the spectra of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole.

FIG. 9b depicts the spectra of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole.

FIG. 10 depicts the spectra of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3.

FIG. 11 depicts the spectra of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3.

FIG. 12 depicts the spectra of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3.

FIG. 13a depicts the spectra of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3.

FIG. 13b depicts the spectra of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3.

FIG. 14 depicts the spectra of5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3′.

FIG. 15 depicts the spectra of5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3′.

FIG. 16a depicts the spectra of5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3′.

FIG. 16b depicts the spectra of5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3′.

FIG. 17 depicts a reaction mechanism.

FIG. 18 depicts a reaction mechanism.

FIG. 19 depicts a reaction mechanism.

FIG. 20 depicts a reaction mechanism.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow.

“Alkyl,” as used herein, refers to an aliphatic hydrocarbon chains. Inone embodiment the aliphatic hydrocarbon chains are of 1 to about 100carbon atoms, preferably 1 to 30 carbon atoms, more preferably, 1 to 20carbon atoms, and even more preferably, and includes straight andbranched chains such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, neo-pentyl, n-hexyl,and isohexyl. In this application alkyl groups can include thepossibility of substituted and unsubstituted alkyl groups.

“Alkylthiol,” as used herein, refers to alkyl groups with a sulfanylgroup (—SH) attached.

“Alkoxy,” as used herein, refers to the group R—O— where R is an alkylgroup of 1 to 100 carbon atoms. In this application alkoxy groups caninclude the possibility of substituted and unsubstituted alkoxy groups.

“Aryl” as used herein, refers to an optionally substituted, mono-, di-,tri-, or other multicyclic aromatic ring systems or heteroaryl systemshaving from about 5 to about 50 carbon atoms (and all combinations andsubcombinations of ranges and specific numbers of carbon atoms therein),with from about 6 to about 20 carbons being preferred. Non-limitingexamples include, for example, phenyl, naphthyl, anthracenyl, andphenanthrenyl. Aryl groups can be optionally substituted with one orwith one or more Rx. In this application aryl groups can include thepossibility of substituted aryl groups, bridged aryl groups, fused aryl,and heteroaryl groups.

“Heteroaryl” as used herein, reference to a heterocyclyl group derivedfrom a heteroarene by removal of a hydrogen atom from any ring atom.Non-limiting substitutions of the ring atom can be S, O, Te, Se, N, P,Si, Ge, B, and As.

“Ester”, as used herein, represents a group of formula —COOR wherein Rrepresents an “alkyl”, “aryl”, a “heterocycloalkyl” or “heteroaryl”moiety, or the same substituted as defined above.

“Ketone” as used herein, represents an organic compound having acarbonyl group linked to a carbon atom such as —C(O)Rx wherein Rx can bealkyl, aryl, cycloalkyl, cycloalkenyl or heterocycle.

“Amide” as used herein, represents a group of formula“—C(O)NR^(x)R^(y),” wherein R^(x) and R^(y) can be the same orindependently H, alkyl, aryl, cycloalkyl, cycloalkenyl or heterocycle.

The following examples of certain embodiments of the invention aregiven. Each example is provided by way of explanation of the invention,one of many embodiments of the invention, and the following examplesshould not be read to limit, or define, the scope of the invention.

Device Architecture

When used as a photovoltaic device the architecture may be aconventional architecture device, while in others it may be an invertedarchitecture device. A conventional architecture device typicallycomprised of multilayered structure with a transparent anode as asubstrate to collect positive charge (holes) and a cathode to collectnegative charge (electrons), and a photo-active layer sandwiched inbetween two electrodes. An additional charge transport interlayer isinserted in between active layer and electrode for facile hole andelectron transport. Each charge transport layer can be consisted of oneor more layers. An inverted device has the same multilayered structureas the conventional architecture device whereas it uses a transparentcathode as a substrate to collect electrons and an anode to collectholes. The inverted device also has the photo-active layer andadditional charge transport layers sandwiched in between two electrodes.FIG. 1 depicts a conventional device architecture and an inverted devicearchitecture.

Constitutional Units to Form Monomers

A variety of constitutional units, or comonomers, that can be used tocreate the monomers for the organic semiconducting polymers. On exampleof a constitutional unit can be unit A

which can be used to form the following comonomer

In this embodiment: W could be S, Se, O, or N-Q; Q a straight-chain orbranched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with1 to 30 atoms, a fused substituted aromatic ring, and a fusedunsubstituted aromatic ring. The fused substituted aromatic rings canfused with H, Cl, F, CN, a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, and anaromatic ring.

In an alternative embodiment, when W is N-Q; Q can be independentlyselected from, H, F, Cl, I, S, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX,—NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′,—SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, or straight-chain carbyl, silyl orhydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms, fused aromaticrings, which can be optionally substituted with one or more X or X′groups; and A and B are H.

In one embodiment, A and B are identical. In another embodiment, A and Bare not identical. In yet another embodiment A and B are independentlyselected from a Br, an aryl group, or heteroaryl group. a monoaromaticgroup, a bi-aromatic group, a tricyclic aromatic group, or aheteroaromatic group. Alternate embodiments of A and B can also include:

wherein W is selected from the group consisting of: C, Si and Se; R′ andR″ can be independently selected from the group consisting of: H, Cl, F,CN, an alkyl group, an alkoxy group, an aryl group, a C₆₋₂₀ alkyl group,a —O—C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkenyl group, a O—C₆₋₂₀ haloalkylgroup, a —S—C₆₋₂₀ alkyl group, a —S—C₆₋₂₀ alkenyl group, a —S—C₆₋₂₀haloalkyl group, a -thienyl-C₆₋₂₀ alkyl group, a -thienyl-C₆₋₂₀ alkenylgroup, and a -thienyl-C₆₋₂₀ haloalkyl group.

Alternate examples of constitutional units include:

In this embodiment: W could be S, Se, 0, or N-Q; Q a straight-chain orbranched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with1 to 30 atoms, a fused substituted aromatic ring, and a fusedunsubstituted aromatic ring. The fused substituted aromatic rings canfused with H, Cl, F, CN, a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, and anaromatic ring.

R′, R″, X, X′, X″, X′″ can be independently selected from the groupconsisting of: H, Cl, F, CN, an alkyl group, an alkoxy group, an arylgroup, a C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkenylgroup, a —O—C₆₋₂₀ haloalkyl group, a —S—C₆₋₂₀ alkyl group, a —S—C₆₋₂₀alkenyl group, a —S—C₆₋₂₀ haloalkyl group, a -thienyl-C₆₋₂₀ alkyl group,a -thienyl-C₆₋₂₀ alkenyl group, and a -thienyl-C₆₋₂₀ haloalkyl group.

Alternative constitutional units or comonomers can also include units B

unit C

or unit D aryl groups. In this embodiment, R₁, R₂, R₃, and R₄ are sidechains independently selected from the group consisting of: H, Cl, F,CN, alkyl, alkoxy, alkylthio, ester, ketone and aryl groups. X1 and X2are independently selected from the group consisting of: H, Cl, F, CN,alkyl, alkoxy, ester, ketone, amide and aryl groups.

The aryl groups of D can be selected from groups such as abenzodithiophenyl group, a silylene-bithiophenyl group, a carbazolylgroup, and a dibenzosilole group, each of which can be optionallysubstituted as described herein. For example, the benzodithiophenylgroup, the silylene-bithiophenyl group, the carbazolyl group, and thedibenzosilole group can be substituted with one, two, three or foursolubilizing groups. Each solubilizing group can be a linear or branchedaliphatic group (e.g., an alkyl group, an alkenyl group, an alkoxygroup, or an alkylthio group) having 6-20 carbon atoms. In particularembodiments, each solubilizing group can be a branched C6-20 alkyl groupor a branch C6-20 alkoxy group. Other examples of aryl groups such aspolycyclic heteroaryl groups of D can include:

In the above examples W can be C, Si or Se. R′, R″ can be independentlyselected from H, Cl, F, CN, an alkyl group, an alkoxy group, an arylgroup, a C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkenylgroup, a —O—C₆₋₂₀ haloalkyl group, a —S—C₆₋₂₀ alkyl group, a —S—C₆₋₂₀alkenyl group, a —S—C₆₋₂₀ haloalkyl group, a -thienyl-C₆₋₂₀ alkyl group,a -thienyl-C₆₋₂₀ alkenyl group, and a -thienyl-C₆₋₂₀ haloalkyl group

In another embodiment, unit E can be

In this embodiment, A can be any aryl and heteroaryl group, preferably amono-, bi- or tricyclic aromatic or heteroaromatic group with up to 40 Catoms that may also comprise condensed rings and is optionallysubstituted with one or more groups R, and wherein one or more carbonatoms are optionally substituted by a heteroatom, which is preferablyselected from N, P, As, O, S, Se and Te. R′ can be selected from: H, F,Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X,—C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH,—NO₂, CF₃, —SF₅, or straight-chain carbyl, silyl or hydrocarbyl,branched, cyclic alkyl with 1 to 30 atoms, fused aromatic rings, whichcan be optionally substituted with one or more X or X′ groups.

In another embodiment, unit F can be

In this embodiment, R and R′ can be the same or different andindependently selected from selected from: H, F, Cl, I, Br, CN, —NCO,—NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′,—C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, orstraight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkyl with1 to 30 atoms, fused aromatic rings, which can be optionally substitutedwith one or more X or X′ groups.

In another embodiment, unit G can be

In this embodiment, R and R′ can be the same or different andindependently selected from, H, F, Cl, I, Br, CN, —NCO, —NCS, —OCN,—SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX,—C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, or straight-chaincarbyl, silyl or hydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms,fused aromatic rings, which can be optionally substituted with one ormore X or X′ groups.

In another embodiment, unit H can be In this embodiment, Q and Q′ can bethe same or different and independently selected from be straight-chaincarbyl, silyl or hydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms,fused aromatic rings, which can be optionally substituted with one ormore X or X′ groups. R′ can be same or different, H, F, Cl, I, Br, CN,—NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX,—NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, orstraight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkyl with1 to 30 atoms, fused aromatic rings, which can be optionally substitutedwith one or more X or X′ groups.

In another embodiment, unit I can be

In this embodiment, Q and Q′ can be the same or different andindependently selected from be straight-chain carbyl, silyl orhydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms, fused aromaticrings, which can be optionally substituted with one or more X or X′groups. R′ can be, H, F, Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX,—SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′,—SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, or straight-chain carbyl, silyl orhydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms, fused aromaticrings, which can be optionally substituted with one or more X or X′groups.

In another embodiment, unit J can be

In this embodiment, Q, Q′, Q″, and Q′″ can be the same or different andindependently selected from straight-chain carbyl, silyl or hydrocarbyl,branched, cyclic alkyl with 1 to 30 atoms, fused aromatic rings, whichcan be optionally substituted with one or more X or X′ groups. R and R′can be same or different, H, F, Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN,—OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX,—C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, or straight-chaincarbyl, silyl or hydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms,fused aromatic rings, which can be optionally substituted with one ormore X or X′ groups.

In some other embodiments, the unit can contain one or more of thefollowing monomer repeat units: a benzodithiophene moiety, a cyclopentadithiazole moiety, a benzothiadiazole moiety, a thiadiazoloquinoxalinemoiety, a benzoisothiazole moiety, a benzothiazole moiety, adithienopyrrole moiety, a dibenzosilole moiety, a thienothiophenemoiety, a carbazole moiety, a dithienothiophene moiety, atetrahydroisoindole moiety, a fluorene moiety, a silole moiety, acyclopentadithiophene moiety, a thiazole moiety, a selenophene moiety, athiazolothiazole moiety, a naphthothiadiazole moiety, a thienopyrazinemoiety, a silacyclopentadithiophene moiety, a thiophene moiety, anoxazole moiety, an imidazole moiety, a pyrimidine moiety, a benzoxazolemoiety, a benzimidazole moiety, a quinoxaline moiety, a pyridopyrazinemoiety, a pyrazinopyridazine moiety, a pyrazino quinoxaline moiety, athiadiazolopyridine moiety, a thiadiazolopyridazine moiety, abenzooxadiazole moiety, an oxadiazolopyridine moiety, anoxadiazolopyridazine moiety, a benzoselenadiazole moiety, abenzobisoxazole moiety, a thienothiadiazole moiety, a thienopyrroledionemoiety, or a tetrazine moiety.

For example, the electron donor or acceptor material can include one ormore of the following monomer repeat units: a benzodithiophene moiety offormula (1), a benzodithiophene moiety of formula (2), acyclopentadithiazole moiety of formula (3), a benzothiadiazole moiety offormula (4), a thiadiazoloquinoxaline moiety of formula (5), abenzoisothiazole moiety of formula (6), a benzothiazole moiety offormula (7), a dithienopyrrole moiety of formula (8), a dibenzosilolemoiety of formula (9), a thienothiophene moiety of formula (10), athienothiophene moiety of formula (11), a carbazole moiety of formula(12), a dithienothiophene moiety of formula (13), a tetrahydroisoindolemoiety of formula (14), a fluorene moiety of formula (15), a silolemoiety of formula (16), a cyclopentadithiophene moiety of formula (17),a thiazole moiety of formula (18), a selenophene moiety of formula (19),a thiazolothiazole moiety of formula (20), a naphthothiadiazole moietyof formula (21), a thienopyrazine moiety of formula (22), asilacyclopentadithiophene moiety of formula (23), a thiophene moiety offormula (24), an oxazole moiety of formula (25), an imidazole moiety offormula (26), a pyrimidine moiety of formula (27), a benzoxazole moietyof formula (28), a benzimidazole moiety of formula (29), a quinoxalinemoiety of formula (30), a pyridopyrazine moiety of formula (31), apyrazinopyridazine moiety of formula (32), a pyrazinoquinoxaline moietyof formula (33), a thiadiazolopyridine moiety of formula (34), athiadiazolopyridazine moiety of formula (35), a benzooxadiazole moietyof formula (36), an oxadiazolopyridine moiety of formula (37), anoxadiazolopyridazine moiety of formula (38), a benzoselenadiazole moietyof formula (39), a benzobisoxazole moiety of formula (40), abenzobisoxazolemoiety of formula (41), a thienothiadiazole moiety offormula (42), a thienopyrroledione moiety of formula (43), or atetrazine moiety of formula (44):

in which each of X and Y, independently, is CH₂, O, or S; each of R₁ andR₂, independently, COR, COOR, CO—N(RR′), C₁-C₂₀ perfluoroalkyl, CN, orSO₃R; in which each of R or R′, independently, is H, C₁-C₂₄ alkyl, aryl,heteroaryl, C₃-C₂₄, cycloalkyl, or C₃-C₂₄ heterocycloalkyl; and each ofR₃, R₄, R₅, R₆, R₇, and R₈, independently, is H, halogen (e.g., F, Cl,Br, or I), C₁-C₂₄ alkyl, C₁-C₂₄ alkoxy, aryl, heteroaryl, C₃-C₂₄cycloalkyl, C₃-C₂₄ heterocycloalkyl, COR″, or COOR″, in which R″ is H,C₁-C₂₄ alkyl, aryl, heteroaryl, cycloalkyl, or C₃-C₂₄ heterocycloalkyl.

Organic Compound/Monomer

In one embodiment, an organic compound, also called a monomer cancomprise:

can be formed.

In this organic compound, W is selected from the group consisting of: S,Se, O, and N-Q; and Q is selected from the group consisting of: astraight-chain or branched carbyl, silyl, or hydrocarbyl, a branched orcyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, anda fused unsubstituted aromatic ring. Additionally, in this organiccompound Ar₁ and Ar₂ are different and selected from aryl units.

In one embodiment of this organic compound, the fused substitutedaromatic ring is fused with: H, Cl, F, CN, a straight-chain or branchedcarbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30atoms, and an aromatic ring.

In another embodiment of the organic compound, Ar₁ and Ar₂ can be thesame, An and Ar₂ can be different, or one Ar₁ or Ar₂ can be H.

In this embodiment, n can be any number of organic compounds necessaryto produce an organic photovoltaic polymer from n=2 to n=1,000, 10,000,even 100,000.

In yet another embodiment, Ar₁, Ar₂ and

are independently selected from:

In yet another embodiment, the organic compounds can be

In this embodiment: W could be S, Se, O, or N-Q; Q a straight-chain orbranched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with1 to 30 atoms, a fused substituted aromatic ring, and a fusedunsubstituted aromatic ring. The fused substituted aromatic rings canfused with H, Cl, F, CN, a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, and anaromatic ring.

R′, R″, X, X′, X″, X′″ can be independently selected from the groupconsisting of: H, Cl, F, CN, an alkyl group, an alkoxy group, an arylgroup, a C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkyl group, a —O—C₆₋₂₀ alkenylgroup, a —O—C₆₋₂₀ haloalkyl group, a —S—C₆₋₂₀ alkyl group, a —S—C₆₋₂₀alkenyl group, a —S—C₆₋₂₀ haloalkyl group, a -thienyl-C₆₋₂₀ alkyl group,a -thienyl-C₆₋₂₀ alkenyl group, and a -thienyl-C₆₋₂₀ haloalkyl group.

Monomer Synthesis

From the above constitutional units of comonomers, any conventionallyknown coupling reaction can be used to make monomers. Examples ofdifferent coupling reactions that can be used include, Wurtz reaction,Glaser coupling, Ullman reaction, Gomberg-Bachmann reaction,Cadiot-Chodkiewicz coupling, Pinacol coupling reaction, Castro-Stephenscoupling, Gilman reagent coupling, Cassar reaction, Kumada coupling,Heck reaction, Sonogashira coupling, Negishi coupling, Stile coupling,Suzuki reaction, Hiyama coupling, Buchwald-Hartwig reaction, Fukuyamacoupling, Liebeskind-Srogl coupling, Direct Heteroarylation andMacMillan coupling.

For examples, as shown in FIG. 2,

4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole can by createdfrom 4-chloro-5-fluorobenzene-1,2-diamine, as shown below.

To begin the process, one must first synthesize4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole. The processbegins by taking 4-chloro-5-fluorobenzene-1,2-diamine and flushing itwith argon. Subsequently, triethylamine was added as solvent and thendichloromethane and thionyl chloride. The resulting mixture was stirredat and cooled down to room temperature and then quenched slowly withwater. The mixture was extracted with dichloromethane. Thedichloromethane layer was dried over anhydrous MgSO4 before the solventwas removed. The results white solid was further purified by flashcolumn with hexane/dichloromethane mixture as eluent. White crystal4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole was obtained asproduct. The H NMRs are shown in FIGS. 3 and 4, and C NMR shown in FIG.5 with the GC-MS as shown in FIGS. 6a and 6 b.

The next step of the process is the synthesis of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole.5-chloro-6-fluoro-2,1,3-benzothiadiazole was put into a Schlenk flaskand flushed with Argon before sulfuric acid and N-Bromosuccinimide wasadded. The reaction was stirred, cooled and, extracted out withchloroform. The organic layer was dried with anhydrous MgSO4 before theremoval of solvent. The resulting solid was purified by column withhexane/dichloromethane as eluent. The C NMRs of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole are shown in FIG. 7 withthe F NMR shown in FIG. 8. GC-MS of4,7-dibromo-5-chlorobenzo[c][1,2,5]thiadiazole are shown in FIGS. 9a and9 b.

The next step is the synthesis of4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3and 5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole3′. 4,7-dibromo-5-chloro-6-fluoro-2,1,3-benzothiadiazole,tributyl(thiophen-2-yl)stannane, and tetrakis(triphenylphosphine)palladium are first combined with anhydrous dimethylformamide. Thereaction is then heated and cooled down to room temperature. The solventwas removed by rotary evaporator and the resulting residue was washedwith hot methanol before purification by silica gel column.Recrystallization from the mixture solvent of IPA/methanol finallyoffered orange crystal as product4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3and 5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole3′. For4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3the H NMR is shown in FIG. 10, C NMR in FIG. 11, F NMR in FIG. 12, andGC-MS shown in FIGS. 13a and 13b . For5-chloro-6-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole 3′ theH NMR is shown in FIG. 14, C NMR in FIG. 15, and GC-MS shown in FIGS.16a and 16 b.

As shown in FIG. 17,

can be used to create both

Synthesis of4-bromo-6-chloro-5-fluoro-7-(4-(alkyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole (0.85 g, 2.45mmol), trimethyl[4-(alkyl)thiophen-2-yl]stannane andtetrakis(triphenylphosphine)palladium(0) Pd(PPh₃)₄ were combined. Afterthe flask was degassed anhydrous dimethylformamide (DMF) was injected.The reaction was heated and cooled down to room temperature. The toluenesolvent was removed under vacuum and the resulting residue was purifiedby silica gel column chromatography with pure hexane as the eluent.Recrystallization from the solvent mixture of isopropanol/hexane (v/v,4:1) afforded red crystals as the product (1.02 g, 66.0%). The ¹H NMRspectrum is shown in FIG. 13.

Synthesis of4-(5-bromo-4-(alkyl)thiophen-2-yl)-7-(5-bromothiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole

4-bromo-6-chloro-5-fluoro-7-(4-(alkyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazolewas added followed by anhydrous THF. The solution was cooled andN-bromosuccinimide was added in portions. The reaction was quenched bythe addition of a saturated potassium carbonate solution and extractedwith hexane. The combined organic layer was dried over anhydrous MgSO4.After the removal of solvent under vacuum, the resulting mixture wassubjected to column chromatography purification with hexane as theeluent. Yellow crystals (0.5 g, 43.1%) were obtained afterrecrystallization from iso-propanol/hexane (v/v, 1:1). The ¹H and ¹³CNMR spectra are shown in FIGS. 14 and 15, respectively.

Synthesis of4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole

4,7-dibromo-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,trimethyl[4-(alkyl)thiophen-2-yl]stannane,tris(dibenzylideneacetone)dipalladium(0) (Pd₂(dba)₃), andtri(o-tolyl)phosphine (P(o-tol)₃) were combined. After the flask wasdegassed, anhydrous toluene was injected. The reaction was heated andcooled down to room temperature. The toluene solvent was removed undervacuum and the resulting residue was purified by silica gel columnchromatography with pure hexane as the eluent. Recrystallization fromthe solvent mixture of isopropanol/hexane (v/v, 4:1) afforded redcrystals as the product (2.46 g, 93.0%). The ¹H NMR spectrum is shown inFIG. 13.

Synthesis of4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole:4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole(2.35 g, 2.571 mmol) was added to a 100-mL Schlenk flask followed by 35mL of anhydrous THF. The solution was cooled to −78° C. andN-bromosuccinimide (0.961 g, 5.4 mmol) was added in portions. Thereaction was stirred overnight at room temperature. The reaction wasquenched by the addition of a saturated potassium carbonate solution andextracted with hexane. The combined organic layer was dried overanhydrous MgSO4. After the removal of solvent under vacuum, theresulting mixture was subjected to column chromatography purificationwith hexane as the eluent. Yellow crystals (2.46 g, 89.3%) were obtainedafter recrystallization from iso-propanol/hexane (v/v, 1:1). The ¹H and¹³C NMR spectra are shown in FIGS. 14 and 15, respectively.

Synthesis of Polymer

4-bromo-7-[5-bromo-4-(alkyl)thiophen-2-yl]-6-chloro-5-fluoro-2,1,3-benzothiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),[4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, Pd₂dba₃tris(dibenzylideneacetone); dipalladium and P(o-tol)₃tris(2-methylphenyl) were combined. The mixture was degassed and ofanhydrous o-dichlorobenzene was injected. The solution was heated andcooled to room temperature. The product was precipitated by pouring thesolution into methanol. The solid was purified by Soxhlet extraction,using acetone, hexane, dichloromethane and chloroform as the solvents.The chloroform portion contained the main product (107 mg, yield 77.8%)after reprecipitation by methanol and then dried overnight.

Anode

When used in as an organic photovoltaic device the polymer can be usedin conjunction with an anode. The anode for the organic photovoltaicdevice can be any conventionally known anode capable of operating as anorganic photovoltaic device. Examples of anodes that can be usedinclude: indium tin oxide, aluminum, silver, carbon, graphite, graphene,PEDOT:PSS, copper, metal nanowires, Zn₉₉InO_(x), Zn₉₈In₂O_(x),Zn₉₇In₃O_(x), Zn₉₅Mg₅O_(x), Zn₉₀Mg₁₀O_(x), and Zn₈₅Mg₁₅O_(x).

Cathode

When used in as an organic photovoltaic device the polymer can be usedin conjunction with a cathode. The cathode for the organic photovoltaicdevice can be any conventionally known cathode capable of operating asan organic photovoltaic device. Examples of cathodes that can be usedinclude: indium tin oxide, carbon, graphite, graphene, PEDOT:PSS,copper, silver, aluminum, gold, metal nanowires.

Electron Transport Layer

When used in as an organic photovoltaic device the copolymer can bedeposited onto an electron transport layer. Any commercially availableelectron transport layer can be used that is optimized for organicphotovoltaic devices. In one embodiment the electron transport layer cancomprise (AO_(x))_(y)BO_((1-y)). In this embodiment, (AO_(x))_(y) andBO_((1-y)) are metal oxides. A and B can be different metals selected toachieve ideal electron transport layers. In one embodiment A can bealuminum, indium, zinc, tin, copper, nickel, cobalt, iron, ruthenium,rhodium, osmium, tungsten, magnesium, indium, vanadium, titanium andmolybdenum.

In one embodiment B can be aluminum, indium, zinc, tin, copper, nickel,cobalt, iron, ruthenium, rhodium, osmium, tungsten, vanadium, titaniumand molybdenum.

Examples of (AO_(x))₄BO_((1-y)) include: (SnO_(x))_(y)ZnO_((1-y)),(AlO_(x))_(y)ZnO_((1-y)), (AlO_(x))_(y)InO_(z(1-y)),(AlO_(x))SnO_(z(1-y)), (AlO_(x))CuO_(z(1-y)), (AlO_(x))_(y)WO_(z(1-y)),(InO_(x))ZnO_((1-y)), (InO_(x))_(y)SnO_(z(1-y)),(InO_(x))_(y)NiO_(z(1-y)), (ZnO_(x))_(y)CuO_(z(1-y)),(ZnO_(x))_(y)NiO_(z(1-y)), (ZnO_(x))_(y)FeO_(z(1-y)),(WO_(x))_(y)VO_(z(1-y)), (WO_(x))_(y)TiO_(z(1-y)), and(WO_(x))_(y)MoO_(z(1-y)).

In an alternate embodiment, various fullerene dopants can be combinedwith (AO_(x))_(y)BO_((1-y)) to make an electron transport layer for theorganic photovoltaic device. Examples of fullerene dopants that can becombined include

and [6,6]-phenyl-C₆₀-butyric-N-2-trimethylammonium ethyl ester iodide.

In the embodiment of

R′ can be selected from either N, O, S, C, or B. In other embodiment R″can be alkyl chains or substituted alkyl chains. Examples ofsubstitutions for the substituted alkyl chains include halogens, N, Br,O, Si, or S. In one example R″ can be selected from

Other examples of fullerene dopants that can be used include:[6,6]-phenyl-C₆₀-butyric-N-(2-aminoethyl)acetamide,[6,6]-phenyl-C₆₀-butyric-N-triethyleneglycol ester and[6,6]-phenyl-C₆₀-butyric-N-2-dimethylaminoethyl ester.

Organic Photovoltaic Device Fabrication

Zinc/tin oxide (ZTO):phenyl-C60-butyric-N-(2-hydroxyethyl)acetamide(PCBNOH) sol-gel solution was prepared by dissolving zinc acetatedihydrate or tin(II) acetate in 2-methoxyethanol and ethanolamine.Specifically, the ZTO:PCBNOH sol-gel electron transport layer solutionwas prepared by mixing Zn(OAc)₂ (3.98 g), Sn(OAc)₂ (398 mg) and PCBNOH(20.0 mg) in 2-methoxyethanol (54 mL) with ethanolamine (996 μL).Solutions were then further diluted to 65 vol % by adding more2-methoxyethanol and stirred for at least an hour before spin castingonto indium tin oxide substrate to form the electron transport layer.

In alternate embodiments, the formation of ZTO([6,6]-phenyl-C₆₀-butyric-N-2-trimethylammonium ethyl ester iodide(PCBNMI) can be used as well. One method of forming PCBNMI can be taking[6,6]-phenyl-C60-butyric-N-2-dimethylaminoethyl ester (0.05 g, 0.052mmol) and dissolved it in dry THF (2 mL) under argon. Iodomethane (1.5mL) was added in one portion and the vessel was sealed. The solution isthen heated to 60° C. for 18 hours. The solution was cooled and openedto allow the liquids to evaporate. The solid residue was suspended inmethanol, diluted with acetone, and centrifuged. This process wasrepeated to produce [6,6]-phenyl-C60-butyric-N-2-trimethylammonium ethylester iodide as a metallic green powder (0.05 g, ˜99% yield).

The polymer and the acceptor, PC₇₀BM, in a ratio of 1:1.2 were dissolvedin chlorobenzene at the concentration of 26 mg/mL to obtain thephotoactive layer solution. The solution was stirred and heated at 80°C. overnight in a nitrogen filled glove box. The next day 3.0 vol % of1,8-diiodooctane (DIO) was added before spin-coating of the photoactivelayer.

Indium tin oxide patterned glass substrates were cleaned by successiveultra-sonications in acetone and isopropanol. Each 15 min step wasrepeated twice, and the freshly cleaned substrates were left to dryovernight at 60° C. Preceding fabrication, the substrates were furthercleaned for 1.5 min in a UV-ozone chamber and the electron transportlayer was immediately spin coated on top.

Sol-gel electron transport layer solution was filtered directly onto theindium tin oxide with a 0.25 μm poly(vinylidene fluoride) filter andspin cast at 4000 rpm for 40 s. Films were then annealed at 170° C. for15 min, and directly transferred into a nitrogen filled glove box.

The photoactive layer was deposited on the electron transport layer viaspin coating at 600 rpm for 40 s with the solution and the substratebeing preheated at 110° C. and directly transferred into a glass petridish for overnight solvent annealing.

After annealing, the substrates were loaded into the vacuum evaporatorwhere MoO₃ (hole transport layer) and Ag (anode) were sequentiallydeposited by thermal evaporation. Deposition occurred at a pressure of<4×10⁻⁶ torr. MoO₃ and Ag had thicknesses of 5.0 nm and 120 nm,respectively. Samples were then encapsulated with glass using an epoxybinder and treated with UV light for 3 min.

Polymer Synthesis

The polymerization can be any conventionally known method of combiningthe comonomers, constitutional units or monomers bonded chain ornetwork. In one non-limiting example polymerization can be via Stillecross coupling, Suzuki cross coupling or direct arylationpolymerization. In another non-limiting example, the polymers createdcan be from 2 to 1,000,000 or even greater repeating units.

In one non-limiting example a polymer can be formed by combining4,7-bis(5-bromo-4-alkylthiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,[4-alkyl-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),Pd₂dba₃ and P(o-tol)₃ to form the polymer:

wherein the ratio of x is between 0.6 to 0.8 and y is between 0.2 and0.4.

In another non-limiting example a polymer can be formed by combining4,7-bis(5-bromo-4-alkylthiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,[4-alkyl-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),Pd₂dba₃ and P(o-tol)₃ to form a mixture; degassing the mixture to form adegassed mixture; heating the degassed mixture to form a heated mixture;and cooling the heated mixture to form the polymer:

wherein the ratio of x is between 0.6 to 0.8 and y is between 0.2 and0.4.

In another example, a polymer can be formed by combining4,7-bis(5-bromo-4-alkyl-thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane), andbenzo[1,2-b:4,5-b]dithiophene-2,6-diyl)bis(trimethylstannane), Pd2dba3and P(o-tol)3 to form the polymer:

wherein the ratio of x is between 0.6 to 0.8 and y is between 0.2 and0.4.

In another example, a polymer can be formed by combining4,7-bis(5-bromo-4-alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane)Pd2dba3and P(o-tol)3 to form a mixture; degassing the mixture to form adegassed mixture; heating the degassed mixture to form a heated mixture;and cooling the heated mixture to form the polymer:

wherein the ratio of x is between 0.6 to 0.8 and y is between 0.2 and0.4.

Examples of polymerization reactions and polymers.

Non-limiting examples of polymers and the associated polymerizationreactions needed to produce them as shown below.

In one embodiment, the polymer can comprise

wherein Ar₁ and Ar₂ are the same or different and independently selectedfrom H or any aryl units. In this polymer, W is selected from the groupconsisting of: S, Se, O, and N-Q; and Q is selected from the groupconsisting of: a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fusedsubstituted aromatic ring, and a fused unsubstituted aromatic ring.Additionally, in the polymer, R₁ is selected from the group consistingof: a straight-chain or branched carbyl, silyl, or hydrocarbyl, abranched or cyclic alkyl with 1 to 30 atoms, a fused substitutedaromatic ring, and a fused unsubstituted aromatic ring and whereinx+y=1.

In yet another embodiment, the polymer can be

wherein x+y=1,

wherein x is from 0.6 to 0.8 and y is from 0.2 to 0.4,

wherein x is from 0.6 to 0.8 and y is from 0.2 to 0.4, or even

wherein x is from 0.6 to 0.8 and y is from 0.2 to 0.4.

In these embodiments, W can be selected from the group consisting of: S,Se, 0, and N-Q; and Q is selected from the group consisting of: astraight-chain or branched carbyl, silyl, or hydrocarbyl, a branched orcyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, anda fused unsubstituted aromatic ring. Additionally, R₁, R₄, and R₅ areindependently selected from the group consisting of: F, Cl, CN, —OX,—SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′,—NO₂, CF₃, —SF₅, a straight-chain or branched carbyl, silyl, orhydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fusedsubstituted aromatic ring, and a fused unsubstituted aromatic ring.Finally, the fused substituted aromatic ring is fused with asubstitution selected from the group consisting of: H, Cl, F, CN, astraight-chain or branched carbyl, silyl, or hydrocarbyl, a branched orcyclic alkyl with 1 to 30 atoms, and an aromatic ring.

Additionally,

can be selected from the group consisting of:

In this embodiment, W could be S, Se, O, or N-Q; Q can be astraight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkyl with1 to 30 atoms, fused aromatic rings, which can be optionally substitutedwith one or more X or X′ groups. R₁ can be selected from F, Cl, I, Br,CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX,—NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅,or straight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkylwith 1 to 30 atoms, fused aromatic rings, which can be optionallysubstituted with one or more X or X′ groups. R₂ and R₃ can be the sameof different and independently selected from any halogen such asfluorine, chlorine. In this embodiment, wherein the ratio of h, j, i,and k are h+j is between 0.2 to 0.6, or more narrowly 0.4, and i+k isbetween 0.4 and 0.8 or more narrowly 0.6.

In a more narrowing embodiment, polymer A can be

In a non-limiting method of manufacturing Polymer A,4-bromo-7-[5-bromo-4-(alkyl)thiophen-2-yl]-6-chloro-5-fluoro-2,1,3-benzothiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),[4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, Pd2dba3tris(dibenzylideneacetone); and dipalladium P(o-tol)3tris(2-methylphenyl)phosphane were combined. The mixture was degassedwith argon and anhydrous o-dichlorobenzene was injected. The solutionwas heated then cooled to room temperature. The product was precipitatedby pouring the solution into methanol. The solid was purified by Soxhletextraction. The chloroform portion contained the main product afterreprecipitation by methanol and then dried overnight. The viscosity ofthe polymer in pure chlorobenzene with the concentration of 10 mg/mL is1.07 mPa·s at 25° C. FIG. 18 depicts one non-limiting method ofmanufacturing Polymer A.

In this embodiment, W could be S, Se, 0, or N-Q; Q can be astraight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkyl with1 to 30 atoms, fused aromatic rings, which can be optionally substitutedwith one or more X or X′ groups. R₁ can be selected from F, Cl, I, Br,CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX,—NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅,or straight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkylwith 1 to 30 atoms, fused aromatic rings, which can be optionallysubstituted with one or more X or X′ groups. R₂ and R₃ can be the sameof different and independently selected from any halogen such asfluorine, chlorine. In this embodiment, wherein the ratio of x isbetween 0.6 to 0.8, or more narrowly 0.6, and y is between 0.2 and 0.4or more narrowly 0.3.

In a more narrowing embodiment, polymer B can be:

In a non-limiting method of manufacturing Polymer B,4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,compound[4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane,compound [4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, Pd2dba3 andP(o-tol)3 were added. The mixture was degassed with argon beforeanhydrous chlorobenzene was added. The solution was heated then cooledto room temperature. The solid was filtered and purified by Soxhletextraction with acetone, hexane, dichloromethane and chloroform. Thechloroform portion contained the main product and was reprecipitated bymethanol and dried overnight. The viscosity of the polymer inchlorobenzene/dichlorobenzene (v/v, 1:1) with the concentration of 10mg/mL is 1.64 mPa·s at 25° C.

In this embodiment, W could be S, Se, O, or N-Q; Q can be astraight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkyl with1 to 30 atoms, fused aromatic rings, which can be optionally substitutedwith one or more X or X′ groups. R₁ can be selected from F, Cl, I, Br,CN, —NCO, —NCS, —OCN, —SCN, —OX, —SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX,—NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′, —SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅,or straight-chain carbyl, silyl or hydrocarbyl, branched, cyclic alkylwith 1 to 30 atoms, fused aromatic rings, which can be optionallysubstituted with one or more X or X′ groups. R₂ and R₃ can be the sameof different and independently selected from any halogen such asfluorine, chlorine, bromine and iodine. R₄ and R₅ can be the same ordifferent and independently selected from straight-chain carbyl, silylor hydrocarbyl, branched, cyclic alkyl with 1 to 30 atoms, fusedaromatic rings, which can be optionally substituted with one or more Xor X′ groups. In this embodiment, wherein the ratio of x is between 0.6to 0.8, or more narrowly 0.6, and y is between 0.2 and 0.4 or morenarrowly 0.3.

In a more narrowing embodiment, polymer C can be:

In other narrowing embodiments, polymer C can be:

In this embodiment, R can be any combination of 2-hexyldecyl,2-butyloctyl, or 2-ethyldexyl. In these embodiments, x and y can be0.7:0.3 respectfully, 0.5:0.5, or x is from 0.6 to 0.8 and y is from 0.2to 0.4. The device performance of the different R's and x:y ratios areshown below in

TABLE 1 Table 1. Jsc R & x:y ratios Voc (V) (mA/cm2) FF(%) PCE (%)2-butyloctyl x = 0.7 y = 0.3 0.817 17.7 71.2 10.3 2-ethylhexyl x = 0.7 y= 0.3 0.811 17.3 74.9 10.7 2-ethylhexyl x = 0.5 y = 0.5 0.799 18.6 64.59.59

Jsc (mA/cm²) Short-circuit current density (Jsc) is the current densitythat flows out of the solar cell at zero bias. V_(oc) (V) Open-circuitvoltage (V_(oc)) is the voltage for which the current in the externalcircuit is zero. Fill factor percentage (FF %) is the ratio of themaximum power point divided by the open circuit voltage and the shortcircuit current. PCE (%) The power conversion efficiency (PCE) of aphotovoltaic cell is the percentage of the solar energy shining on aphotovoltaic device that is converted into usable electricity.

In a non-limiting method of manufacturing Polymer C,4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,compound [4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, compound[4-(2-hexyldecyl)-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, Pd2dba3 andP(o-tol)3 were added. The mixture was degassed with argon beforeanhydrous chlorobenzene was added. The solution was heated then cooledto room temperature. The solid was filtered and purified by Soxhletextraction with acetone, hexane, dichloromethane and chloroform. Thechloroform portion contained the main product and was reprecipitated bymethanol and dried overnight. The viscosity of the polymer inchlorobenzene/dichlorobenzene (v/v, 1:1) with the concentration of 10mg/mL is 1.50 mPa·s at 25° C. FIG. 19 depicts a non-limiting method ofmanufacturing Polymer B and Polymer C.

wherein R₁ is C₆H₁₃.

In a non-limiting embodiment, polymer D can be formed by combining4-(5-bromo-4-(alkyl)thiophen-2-yl)-7-(5-bromothiophen-2-yl)-6-chloro-5-fluorobenzo[c][1,2,5]thiadiazole,(4,8-bis(5-(2-butyloctyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane),Pd2dba3 and P(o-tol)3 together. The mixture is then degassed with argonbefore adding anhydrous chlorobenzene. The solution is then heatedfollowed by chloroform addition. The solid was filtered and purified bySoxhlet extraction with methanol, hexane and chloroform. The viscosityin chlorobenzene/dichlorobenzene (v/v, 1:1) with concentration of 10mg/mL is 1.255 mPa·s at 25° C.

wherein R₁ is C₂H₅.

In a non-limiting embodiment, polymer E can be formed by combining4-(5-bromo-4-(alkyl)thiophen-2-yl)-7-(5-bromothiophen-2-yl)-6-chloro-5-fluorobenzo[c][1,2,5]thiadiazole,compound(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane),Pd2dba3 and P(o-tol)3. The mixture is then degassed before addinganhydrous dichlorobenzene. The solution was heated and poured intomethanol. The solid was filtered and purified by Soxhlet extraction withacetone, hexane and dichloromethane. The solid product was collectedfrom the dichloromethane portion, reprecipitated with methanol, anddried overnight. The viscosity in chlorobenzene/dichlorobenzene (v/v,1:1) with concentration of 10 mg/mL is 1.15 mPa·s at 25° C.

In a 25-mL Schlenk flask,4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole(100.0 mg, 0.093 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene(46.7 mg, 0.095 mmol), Pd₂dba₃ (1.1 mg, 0.001 mmol) and P(o-tol)₃ (2.4mg, 0.008 mmol) were added. The mixture was degassed with argon threetimes before 1.6 mL of anhydrous chlorobenzene was added. The mixturewas further degassed with two freeze-vacuum-thaw cycles. The solutionwas heated at 90° C. for 10 mins and at 120° C. for 48 hours to avoidoverheating. The mixture was poured into methanol after cooling to roomtemperature. The solid was filtered and purified by Soxhlet extractionwith acetone (16 hours), hexane (3 hours) chloroform (4 hours) andchlorobenzene (5 hours). The recovered polymer consisted of 27 mg(yield, 26.3%) from the chloroform portion, 8 mg (yield, 7.8%) from thechlorobenzene portion and 65 mg remained insoluble in the thimble.

In a 25-mL Schlenk flask,4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole(100.0 mg, 0.093 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene(46.7 mg, 0.095 mmol) and P(o-tol)₃ (2.4 mg, 0.008 mmol) were added. Theflask was degassed with argon three times before 1.6 mL of anhydrousdichlorobenzene was added. The solution was heated at 135° C. for 48hours. The mixture was poured into methanol after cooling to roomtemperature. The solid was filtered and purified by Soxhlet extractionwith acetone (8 hours), hexane (16 hours) and chloroform (3 hours).There was nothing left in the thimble. The chloroform portion was themain product (88 mg, yield, 85.6%). It was collected afterreprecipitation from methanol and dried overnight. The viscosity of thepolymer in chlorobenzene/dichlorobenzene (v/v, 1:1) with theconcentration of 10 mg/mL is 1.36 mPa·s at 25°.

In the above polymerizations, dichlorobenzene was used in most of thereactions since when using chlorobenzene as the solvent, the yieldsignificantly decreased from 85.6% to 34.1% due to crosslinking in thepolymer as shown in Table 2 below.

TABLE 2 Polymers Solvent Yield (%) Polymer F-1 Chlorobenzene 34.1Polymer F-2 Dichlorobenzene 85.6

It is theorized that using a solvent that selected from the groupconsisting of: dichlorobenzene, trichlorobenzene, or combinationsthereof would allow of selectivity yields greater than 40%, 50%, 60%,70%, even 80%. As shown in FIG. 20, the reaction mechanism for F1 and F2provided low yields when performed without the appropriate solvent. Itis theorized that the chlorine atom participates in the couplingreaction with tin compound leading to crosslinking.

Synthesis of5-chloro-7-(5-(2-ethylhexyl)thiophen-2-yl)-6-fluoro-4-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole4 and4,6-bis(5-(2-ethylhexyl)thiophen-2-yl)-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole5: In a 25 mL Schlenk flask,(5-(2-ethylhexyl)thiophen-2-yl)trimethylstannane (260 mg, 0.724 mmol),4-bromo-6-chloro-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole(230 mg, 0.658 mmol), Pd₂dba₃ (12 mg, 0.013 mmol) and P(o-tol)₃ (16 mg,0.053 mmol) were combined. The mixture was degassed three times before7.7 mL of anhydrous toluene was injected. The solution was heated to105° C. for 48 h and then cooled to room temperature. The toluenesolvent was removed by a rotary evaporator, and the resulting residuewas purified by using silica gel column chromatography withhexane/dichloromethane mixture as the eluent. The two products werecollected as separate fractions. The compounds were both recrystallizedfrom the solvent mixture of iso-propanol/methanol to yield compound5-chloro-7-(5-(2-ethylhexyl)thiophen-2-yl)-6-fluoro-4-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole(0.13 g, yield 31.6%) and4,6-bis(5-(2-ethylhexyl)thiophen-2-yl)-5-fluoro-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole(0.04 g, yield 13.1%) as orange crystals.

In a non-limiting embodiment, Polymer G can be formed by combining4,7-bis(5-bromo-4-(alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole,compound(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),Pd2dba3 and P(o-tol)3 were added. The solution was degassed beforeanhydrous dichlorobenzene was added. The solution was then heated andcooled to room temperature. The solid was filtered and purified bySoxhlet extraction with acetone, hexane, dichloromethane, chloroform andchlorobenzene.

Electron Transport Layer:

Zinc tin oxide (ZTO): phenyl-C₆₀-butyric acid-2-N,N,N-trimethylammoniumiodide ethyl ester (PCBNMI) sol-gel solutions were prepared by addingzinc acetate dihydrate (996 mg), tin (II) acetate (99.6 mg), and PCBNOH(5 mg) to 2-methoxyethanol (10 mL) and ethanolamine (249 μL). Solutionswere stirred for a minimum of 8 hours before use.

An Erichsen COATMASTER 510 was used to spread the electron transportlayer on the large area ITO substrates. Approximately 300 μL of the zinctin oxide:fullerene (ZTO:PCBNMI) sol-gel solution was drawn into apipette and deposited without filtration, directly onto the ITO at roomtemperature.

Table 3 below depicts the average device performance of theabove-mentioned polymers.

TABLE 3 Active Layer Voc (V) Jsc (mA/cm2) FF(%) PCE (%) Polymer A 0.7917.44 65.8 8.73 Polymer B 0.829 15.5 74.3 9.5 Polymer C 0.853 16.8 69.69.98 Polymer D 0.872 9.42 66.3 5.44 Polymer E 0.823 15.24 65.1 8.16Polymer F 0.731 16.2 71.4 8.46 Polymer G 0.815 12.8 45.5 4.76

Jsc (mA/cm²) Short-circuit current density (Jsc) is the current densitythat flows out of the solar cell at zero bias. V_(oc) (V) Open-circuitvoltage (V_(oc)) is the voltage for which the current in the externalcircuit is zero. Fill factor percentage (FF %) is the ratio of themaximum power point divided by the open circuit voltage and the shortcircuit current. PCE (%) The power conversion efficiency (PCE) of aphotovoltaic cell is the percentage of the solar energy shining on aphotovoltaic device that is converted into usable electricity.

Devices in which the photovoltaic polymer, copolymer, unit, or processcan be used in include, but are not limited to general organicphotovoltaic devices, organic light emitting diodes, transistors,photodetectors, and radio frequency identification tags.

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as an additional embodiment of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

1. A method of forming a polymer, the method comprising: combining4,7-bis(5-bromo-4-alkyl-thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]-thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane), andbenzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane), Pd₂dba₃and P(o-tol)₃ to form the polymer:

W is selected from the group consisting of: S, Se, O, and N-Q; Q isselected from the group consisting of: a straight-chain or branchedcarbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30atoms, a fused substituted aromatic ring, and a fused unsubstitutedaromatic ring; R₁, R₂, R₃, R₄, and R₅ are independently selected fromthe group consisting of: F, Cl, I, Br, CN, —NCO, —NCS, —OCN, —SCN, —OX,—SX, —NH₂, —C(═O)X, —C(═O)—OX, —OX, —NHX, —NXX′, —C(═O)NHX, —C(═O)NXX′,—SO₃X, —SO₂X, —OH, —NO₂, CF₃, —SF₅, a straight-chain or branched carbyl,silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, afused substituted aromatic ring, and a fused unsubstituted aromaticring, and heteroaromatic rings; wherein the fused aromatic rings can beindependently fused with groups consisting of: a straight-chain orbranched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with1 to 30 atoms, a fused substituted aromatic ring, and a fusedunsubstituted aromatic ring; and wherein the ratio of x is between 0.6to 0.8 and y is between 0.2 and 0.4.
 2. A method of forming a polymer,the method comprising: combining4,7-bis(5-bromo-4-alkyl)thiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]-thiadiazole,(3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane),benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane)Pd₂dba₃and P(o-tol)₃ to form a mixture; degassing the mixture to form adegassed mixture; heating the degassed mixture to form a heated mixture;and cooling the heated mixture to form the polymer:

wherein the ratio of x is between 0.6 to 0.8 and y is between 0.2 and0.4.